Methods for preparing epoxides

ABSTRACT

The invention includes methods for preparing halohydrins and epoxides. A method of preparing halohydrins can include exposing (R 1 CHXCH 2 O—) 2 SO 2  to R 2 COOH to produce R 2 COOCH 2 CHXR 1  and hydrolyzing the R 2 COOCH 2 CHXR 1  to produce the halohydrin R 1 CHXCH 2 OH. R 1  and R 2  can be the same or different single elements and/or organic groups and X can be a halogen. A method of preparing an epoxide can include combining a sulfuric acid containing solution with a halogen to produce a first mixture and exposing the first mixture to trifluoropropene to produce a second mixture. The second mixture can be combined with acetic acid to produce an acetyl halohydrin of trifluoropropene and the acetyl halohydrin can be hydrolyzed to form a halohydrin of trifluoropropene. The halohydrin can be converted to a trifluoropropyl epoxide.

RELATED PATENT DATA

This patent is a divisional of U.S. patent application Ser. No. 11/809,821, which was filed Jun. 1, 2007, which claims priority to U.S. provisional patent application 60/810,408, which was filed Jun. 2, 2006, entitled “Methods for Preparing Halohydrins and Methods for Preparing Epoxides” all of which are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to methods for preparing halohydrins and methods for preparing epoxides.

BACKGROUND OF THE INVENTION

Polymers can be produced by polymerizing monomers having epoxide functionality. Monomers having epoxide functionality can be produced from monomers having halogenated carbons and hydroxyl groups situated adjacent the halogenated carbon. Compounds having this functionality are referred to as halohydrins. An exemplary halohydrin is CF₃CHBrCH₂OH.

Methods for preparing halohydrins and are provided.

SUMMARY OF THE INVENTION

The present invention provides methods for preparing halohydrins and epoxides. In one implementation, a method of preparing halohydrins includes exposing (R¹CHXCH₂O—)₂SO₂ to R²COOH to produce R²COOCH₂CHXR¹ and hydrolyzing the R²COOCH₂CHXOR¹ to produce the halohydrin R¹CHXCH₂OH. R¹ and R² can be the same or different single elements and/or organic groups and X can be a halogen.

In one implementation, a method of preparing a halohydrin includes exposing a di(perhaloalkyl)haloethyl sulfate to a carboxylic acid compound to produce a (perhaloalkyl)haloethyl alkyl ester, and subsequently hydrolyzing the (perhaloalkyl)haloethyl alkyl ester to produce the halohydrin.

In one implementation, a method of preparing an epoxide includes combining a sulfuric acid containing solution with a halogen to produce a first mixture and exposing the first mixture to trifluoropropene (TFP) to produce a second mixture. The second mixture can be combined with acetic acid to produce an acetyl halohydrin of trifluoropropene and the acetyl halohydrin can be hydrolyzed to form a halohydrin of trifluoropropene. The halohydrin can be converted to a trifluoropropyl epoxide.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawing.

The FIGURE is an illustration of a synthetic scheme according to one aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).

In one aspect the present invention includes methods for preparing halohydrins. Another aspect of the present invention includes methods for preparing epoxides. Various exemplary aspects of the present invention are described with reference to the FIGURE. The FIGURE depicts a synthetic scheme according to one aspect of the present invention for producing halohydrins and epoxides. In this exemplary depiction a four step synthetic scheme is illustrated (with the steps being A, B, C, and D, respectively). The present invention is not limited to this four step synthetic scheme. Persons having ordinary skill in the art will be able to modify and combine synthetic steps using the detailed description of the present invention.

Synthetic step A depicts the conversion of an olefin to a sulfate. The olefin can include compounds having the generic formula R¹CH═CH₂. R¹ can include organic groups such as CF₃— or single elements such as H and/or halogens such as I, Br, Cl, or F. It has been generalized to include every possible olefin. R¹ can also include saturated and unsaturated carbon chains of organic compounds. An exemplary olefin for use in accordance with the present invention can be trifluoropropene (CF₃CH═CH₂). The conversion of the olefin to the sulfate can include exposing the olefin to a halogen and sulfuric acid. The sulfuric acid can be in the form of a solution. An exemplary sulfuric acid containing solution can be oleum. Oleum can be a solution of H₂SO₄ that includes free SO₃ and up to as high as 80% (wt./wt.) free SO₃. The halogen can be provided in diatomic form, such as, for example, 12, Br₂, or Cl₂.

The halogen and oleum can be in the form of a halogen-oleum mixture. The halogen-oleum mixture can be prepared by combining the halogen with oleum. The halogen-oleum mixture can include a Br₂-oleum mixture. The Br₂-oleum mixture can contain at least about 20% (wt./wt.) oleum. The oleum to bromine mole ratio of the Br₂-oleum mixture, in one aspect, can be at least 1:0.7, in another aspect, from about 1:0.7 to about 4:0.7 and, in a further aspect, can be about 2:0.8.

In an exemplary aspect, the olefin can be exposed to the halogen and oleum by bubbling the olefin in gas form into the halogen-oleum mixture. The olefin can also be exposed to the halogen-oleum mixture at a temperature from about 12° C. to about 22° C. The mole ratio of the olefin, the oleum, and the Br₂ during exposing, in one aspect, can be from about 1:1:0.7 to about 1:4:0.8 and in another aspect, at least about 1:2:0.8.

A sulfate can be produced upon exposure of the olefin to the halogen-oleum mixture. The sulfate can have the general formula (R¹CHXCH₂O—)₂SO₂.

(R¹CHXCH₂O—)₂SO₂ can include di(perhaloalkyl)haloethyl sulfates and more particularly (CF₃CHXCH₂O—)₂SO₂ and even more particularly (CF₃CHBrCH₂O—)₂SO₂. In an exemplary aspect, (CF₃CHBrCH₂O—)₂SO₂ can be produced upon exposure of trifluoropropene to a Br₂-oleum mixture.

Referring next to scheme B of the FIGURE, an acetyl halohydrin can be produced, in an exemplary aspect, upon exposure the sulfate to a carboxylic acid compound. The carboxylic acid compound generally has the formula R²COOH. R² can include the functional group CH₃—, but may also include branched organic groups such as (CH₃)₂CH—. R² can also include single elements such as H and/or halogens such as 1, Br, Cl, or F. R² can be the same or different from R¹. An exemplary carboxylic acid compound includes acetic acid.

The acetyl halohydrin can have the general formula R²COOCH₂CHXR¹. R²COOCH₂CHXR¹ also includes (perhaloalkyl)haloethyl alkyl esters. Exemplary acetyl halohydrins include R²COOCH₂CHBrR¹, CH₃COOCH₂CHXCF₃ and more particularly CH₃COOCH₂CHBrCF₃. R²COOCH₂CHBrR¹ can generally be referred to as an acetyl bromohydrin.

Referring next to scheme C of the FIGURE, the acetyl halohydrin is hydrolyzed in one aspect to produce the halohydrin. In one implementation, the acetyl halohydrin can be hydrolyzed by exposing the acetyl halohydrin to a sulfuric acid solution. An exemplary sulfuric acid solution includes at least about 15% (wt./wt.) sulfuric acid. The halohydrin can have the general formula R¹CHXCH₂OH. R¹CHXCH₂OH can include CF₃CHXCH₂OH as well as CF₃CHBrCH₂OH. R¹CHBrCH₂OH can generally be referred to as a bromohydrin.

Referring to scheme D of the FIGURE, the halohydrin can be converted in one aspect to an epoxide in the presence of a base. In an exemplary aspect the halohydrin is exposed to a basic solution to produce the epoxide. The basic solution can comprise at least about 20% (wt./wt.) sodium hydroxide and/or from about 40% to about 70% sodium hydroxide as well as from about 50% to about 60% sodium hydroxide. The conversion of the halohydrin to the epoxide can also occur at a temperature of at least about 100° C. or from about 100° C. to about 130° C. The epoxide can have the general formula R¹CHCH₂(O). R¹CHCH₂(O) can also include CF₃CHCH₂(O) and trifluoropropyl epoxide. In an exemplary embodiment (not shown) the epoxide may be utilized as a monomer in the production of polymers. An exemplary polymer can include fluoropolymers having at least one CF₃— group.

Aspects of the present invention will now be described with reference to the following non-limiting examples.

Example 1

TABLE 1 MW Mmoles equivalents Quantity TFP 96  0.186 1 18 g Oleum 20% 0.375 2 150 g Br₂ 160  0.180 0.97 28.7 g CH₃COOH n/a n/a n/a 300 ml

In accordance with example 1, 150 g of oleum is taken in a 500 ml three-necked round-bottomed flask fitted with a dry ice condenser and a bubbler (TFP inlet tube) to which 28.7 g. Br₂ is then added to form a bromine-oleum mixture. The bromine-oleum mixture is stirred at room temperature for 3 hrs. The round-bottomed flask is covered with aluminum foil. TFP (18 g) is then bubbled through the mixture to form a reaction mixture. The rate of TFP addition is adjusted so that the temperature of the reaction mixture remains from about 12° C. to about 22° C. Upon addition of the TFP the bromine color is nearly gone, and the reaction mixture is stirred at room temperature for 1 hour. The reaction mixture is then poured into 300 ml of acetic acid taken in a 500 ml single-neck round-bottomed flask, stirred, and heated to 100° C. for 1 hr. This solution is cooled to room temperature and 100 ml of water is added and extracted four times with 100 ml portions of dichloromethane. (Dichloromethane forms an upper layer). Organic layers are combined and washed with saturated NaHCO₃ (4×200 ml), dried over anhydrous Na₂SO₄ (150 g.) and evaporated (without applying vacuum) to yield acetyl bromohydrin (43.9 g.) as a clear colorless liquid. Yield=43.9 g. (99.6%), ¹H NMR: (CDCl₃, 300 MHz), δ ppm: 2.12 (s, 3H), 4.34-4.56 (m, 3H)

Example 2

Acetyl bromohydrin 180 g. Conc. H₂SO₄ 100 ml H₂O 1000 ml

In accordance with example 2, 1 L of water is placed in a 2 L single-necked round-bottomed flask fitted with a condenser. Concentrated H₂SO₄ (100 ml) is added slowly to the flask to produce a reaction mixture. Acetyl bromohydrin (180 g) is then added and the mixture is heated to reflux. The mixture is refluxed for 3 hrs until the mixture becomes homogeneous and further refluxed for 1 hour and then cooled to room temperature. The reaction mixture is saturated with NaCl and extracted with ether (200 ml×5). Combined ether layers are washed with saturated NaHCO₃, dried over anhydrous Na₂SO₄ and evaporated to yield bromohydrin 131 g. Yield=131 g. (89%) ¹H NMR (CDCl₃, 300 MHz) δ ppm: 3.90-4.02 (m, 1H), 4.04-4.14 (m, 1H), 4.22-4.34 (m, 1H).

Example 3

Bromohydrin 65 g. Aq. NaOH (20%) 100 g.

In accordance with example 3, 65 g. bromohydrin is taken in a 300 ml three-necked round-bottomed flask fitted with a septum, a thermometer jacket, and a distillation set up. The bromohydrin is stirred and heated to 85° C. (oil bath temperature was 95° C.). NaOH (20% solution, 100 g) is introduced through septum by syringe. Product distills as NaOH is introduced. Yield=26 g. (69%) ¹H NMR: (CDCl₃, 300 MHz) δ ppm: 2.90-2.94 (m, 1H), 2.96-3.02 (m, 1H), 3.38-3.46 (m, 1H).

In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents. 

1-49. (canceled) 50: A method of preparing an epoxide comprising: combining a sulfuric acid containing solution with a halogen to produce a first mixture; exposing the first mixture to trifluoropropene to produce a second mixture; combining the second mixture with acetic acid to produce an acetyl halohydrin of the trifluoropropene; hydrolyzing the acetyl halohydrin to form a halohydrin of trifluoropropene; and converting the halohydrin to a trifluoropropyl epoxide. 51: The method of claim 50 wherein the halogen is Br₂, the acetyl halohydrin is acetyl bromohydrin, the sulfuric acid containing solution is oleum, and the halohydrin of trifluoropropene is the bromohydrin of trifluoropropene. 52: The method of claim 51 wherein the first mixture contains a ratio of oleum to bromine of at least 1:0.7. 53: The method of claim 51 wherein the first mixture contains a ratio of oleum to bromine of from about 1:0.7 to about 4:0.7. 54: The method of claim 51 wherein the first mixture contains a ratio of oleum to bromine of about 2:0.8. 55: The method of claim 50 wherein the exposing comprises maintaining the first mixture at a temperature of from about 12° C. to about 22° C. while bubbling the trifluoropropene into the first mixture. 56: The method of claim 51 wherein the second mixture comprises (CF₃CHBrCH₂O—)SO₂. 57: The method of claim 51 wherein the hydrolyzing comprises exposing the acetyl bromohydrin to a sulfuric acid solution. 58: The method of claim 57 wherein the sulfuric acid solution comprises at least about 15% (wt./wt.) sulfuric acid. 59: The method of claim 51 wherein the converting comprises exposing the bromohydrin to a basic solution. 60: The method of claim 59 wherein the basic solution comprises at least about 20% (wt./wt.) sodium hydroxide. 61: The method of claim 59 wherein the basic solution comprises from about 40% (wt./wt.) to about 70% (wt./wt.) sodium hydroxide. 62: The method of claim 59 wherein the basic solution comprises from about 50% (wt./wt.) to about 60% (wt./wt.) sodium hydroxide. 63: The method of claim 50 wherein the converting occurs at a temperature of at least about 100° C. 64: The method of claim 50 wherein the converting occurs at a temperature of from about 100° C. to about 130° C. 